Exemplary embodiments relate to a brush seal assembly, and more particularly, to a brush seal assembly for sealing a gap between a diaphragm and a rotor of a turbine.
Generally, a turbine is a power generation apparatus which converts heat energy of a fluid such as gas or steam into mechanical energy, and includes a rotor having a plurality of buckets to axially rotate by the fluid and a casing which is installed to surround the rotor and has a plurality of diaphragms.
A gas turbine includes a compressor, a combustor, and a turbine. In the gas turbine, outside air is introduced and compressed by rotation of the compressor and is then transferred to the combustor, and combustion is performed by mixture of the compressed air and fuel in the combustor. High-temperature and high-pressure gas generated by the combustor drives a generator by rotating a rotor of the turbine while passing through the turbine.
In a steam turbine, a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine are interconnected in series or in parallel to rotate a rotor. When the steam turbine has a series structure, the high-pressure turbine, the intermediate-pressure turbine, and the low-pressure turbine share one rotor.
In the steam turbine, each turbine has a diaphragm and a bucket on the basis of the rotor in a casing. Steam rotates the rotor while passing through the diaphragm and the bucket to drive a generator.
Since each of the gas turbine and the steam turbine has a structure in which a rotary body (for instance, a rotor) is rotated relative to a stationary body (for instance, a diaphragm), a high-temperature and high-pressure fluid is leaked to a gap between the stationary body and the rotary body and such a fluid leak causes deterioration of energy efficiency due to a power loss. For this reason, an effort for reduction of the fluid leak generated through the gap between the rotary body and the stationary body may be made.
The gap between the rotary body and the stationary body may be decreased to reduce the fluid leak, but there are various limits in decreasing the gap.
When the gap is excessively small, vibration is caused by rubbing due to interference between the rotary body and the stationary body when the rotary body axially rotates, and may result in serious damage of devices.
Meanwhile, since the rotary body and the stationary body are heated by hot steam introduced from a boiler in the steam turbine, the rotary body and the stationary body are expanded or contracted from several mm to several tens of mm according to positions thereof when the steam turbine is operated or stopped. In this case, the rotary body and the stationary body are differently expanded because of being made of different materials, and are expanded in different directions according to the structure of the turbine. For this reason, the rotary body interferes with the stationary body when the steam turbine is operated, thereby causing the rubbing.